OJB中的多表查询和更新

最新推荐文章于 2021-02-19 07:21:04 发布

转载最新推荐文章于 2021-02-19 07:21:04 发布 · 984 阅读

文章标签：

#class #import #integer #string #iterator #delete

举个例子，课程(event)和分类(catalog)二者是多对多的关系，对应关系在表catalogEventBridge中，字段为[catalogID,eventID]，现在做的是当查询或者修改一个catalog的时候，对应的event在bridge表中也要修改

1.修改repository_user.xml

<class-descriptor class="org.pie.vls.Catalog.Catalog" table="catalog">
<field-descriptor name="catalogID" column="catalogID" jdbc-type="INTEGER" primarykey="true" />
<field-descriptor
name="catalogName"
column="catalogName"
jdbc-type="VARCHAR" />
<collection-descriptor name="catalogEventList"
element-class-ref="org.pie.vls.Catalog.CatalogEventBridge"
auto-retrieve="true"
auto-update="true"
auto-delete="true">
<inverse-foreignkey field-ref="catalogID"/>
</collection-descriptor>
</class-descriptor>
<class-descriptor class="org.pie.vls.Catalog.CatalogEventBridge" table="catalogEventBridge">
<field-descriptor
name="catalogID"
column="catalogID"
jdbc-type="INTEGER"
primarykey="true" />
<field-descriptor
name="eventTypeID"
column="eventTypeID"
jdbc-type="INTEGER"
primarykey="true" />
</class-descriptor>
<class-descriptor
class="org.pie.vls.EventType.EventType" table="eventType" >
<field-descriptor
name="eventTypeID"
column="eventTypeID"
jdbc-type="INTEGER"
primarykey="true"
autoincrement="true" />
<field-descriptor
name="eventTypeTitle"
column="eventTypeTitle"
jdbc-type="VARCHAR"
/>
... ...
</class-descriptor>

2. bean文件的定义

EventType.java

public class EventType implements Cloneable, Comparable {
private String eventTypeTitle;
private String eventTypeCode;
private String eventTypeDesc;
private int eventTypeID;
public int getEventTypeID() {
return this.eventTypeID;
}
public void setEventTypeID(int value) {
this.eventTypeID = value;
}
... ...
}

catalog.java

public class Catalog implements Comparable {
private int catalogID;
private String catalogName = "";
private List catalogEventList = new Vector();
/**
* @return Returns the catalogID.
*/
public int getCatalogID() {
return catalogID;
}
/**
* @param catalogID The catalogID to set.
*/
public void setCatalogID(int catalogID) {
this.catalogID = catalogID;
}
/**
* @return Returns the catalogName.
*/
public String getCatalogName() {
return catalogName;
}
/**
* @param catalogName The catalogName to set.
*/
public void setCatalogName(String catalogName) {
this.catalogName = catalogName;
}
/**
* @return Returns the catalogEventList.
*/
public List getCatalogEventList() {
return catalogEventList;
}
/**
* @param catalogEventList The catalogEventList to set.
*/
public void setCatalogEventList(List catalogEventList) {
this.catalogEventList = catalogEventList;
}
}

CatalogEventBridge.java

public class CatalogEventBridge {
private int catalogID = 0;
private int eventTypeID = 0;
/**
* @return Returns the catalogID.
*/
public int getCatalogID() {
return catalogID;
}
/**
* @param catalogID The catalogID to set.
*/
public void setCatalogID(int catalogID) {
this.catalogID = catalogID;
}
/**
* @return Returns the eventTypeID.
*/
public int getEventTypeID() {
return eventTypeID;
}
/**
* @param eventTypeID The eventTypeID to set.
*/
public void setEventTypeID(int eventTypeID) {
this.eventTypeID = eventTypeID;
}
}

3. DAO文件

import java.util.Collection;
import java.util.Iterator;
import org.apache.log4j.Logger;
import org.apache.ojb.broker.PersistenceBroker;
import org.apache.ojb.broker.PersistenceBrokerFactory;
import org.apache.ojb.broker.query.Criteria;
import org.apache.ojb.broker.query.QueryByCriteria;
import org.apache.ojb.broker.query.QueryFactory;
import org.odmg.Implementation;
import org.pie.vls.Application.AbstractVLSBase;
public class CatalogDAO extends AbstractVLSBase {
private Collection catalogList;
private PersistenceBroker broker;
private static final Logger logger = Logger.getLogger(Catalog.class);
private int catalogID = 0;
public CatalogDAO(Implementation impl) {
super(impl);
init();
}
public CatalogDAO(Implementation impl, int catalogID) {
super(impl);
this.catalogID = catalogID;
init();
}
/* (non-Javadoc)
* @see org.pie.vls.Application.VLSBase#init()
*/
public void init() {
// TODO Auto-generated method stub
try {
broker = PersistenceBrokerFactory.defaultPersistenceBroker();
broker.clearCache();
Criteria crit = new Criteria();
if (this.catalogID > 0) {
crit.addEqualTo("catalogID", new Integer(this.catalogID));
}
QueryByCriteria tquery = QueryFactory.newQuery(Catalog.class, crit);
this.catalogList = broker.getCollectionByQuery(tquery);
broker.clearCache();
broker.close();
} catch (Throwable t) {
logger.error(t.getMessage(), t);
}
}
public boolean isEmpty(){
return this.catalogList.isEmpty();
}
public Collection getCatalogList() {
return this.catalogList;
}
public Catalog getCatalog() {
Iterator iter = this.catalogList.iterator();
Catalog catalog = (Catalog) iter.next();
return catalog;
}
public void create(Catalog catalog) {
update(catalog);
}
public void update(Catalog catalog) {
try {
broker = PersistenceBrokerFactory.defaultPersistenceBroker();
broker.clearCache();
broker.beginTransaction();
broker.store(catalog);
broker.commitTransaction();
broker.close();
} catch (Throwable t) {
logger.error(t.getMessage(), t);
}
}
public void delete(Catalog catalog) {
try {
broker = PersistenceBrokerFactory.defaultPersistenceBroker();
broker.clearCache();
broker.beginTransaction();
broker.delete(catalog);
broker.commitTransaction();
broker.close();
} catch (Throwable t) {
logger.error(t.getMessage(), t);
}
}
}

catalogEventBridgeDAO.java和ÍeventTypeDAO.java跟上面的DAO文件类似，就不多说了。

使用起来就方便多了，只要实例化CatalogDAO，然后得到查询结果，一个catalog的集合，然后通过catalog.getCatalogEventList()的方法来就得到了一个bridge的集合。
还可以通过catalogDAO的create,update和delete方法来更新catalog同时也更新catalogEventBridge表中的数据